TFT liquid crystal display devices are now becoming increasingly popular for its lightness, environmental friendliness, and high performance. Required by the wider application domains, liquid crystal display devices are becoming larger and larger in size. At present, the screen of a 65-inch single screen liquid crystal display device can have a resolution of 1920*1080. At such a high integration level, defects of the products will also increase. Therefore, it is of great importance to reinforce quality detection of liquid crystal display devices in mass production, detect the defects of sampled array substrates and analyze causes of the defects.
In existing technologies, there is not yet an effective method for detecting the above defects. So far, the detection is mainly performed by a detector who judges an abnormal area possibly having defects based on his/her experience, and cuts the abnormal area for analysis. This method can only roughly position a potentially defective thin film transistor, but cannot accurately find the specific layer where the abnormity exists. Besides, after the abnormal point is found by cutting the abnormal area, it is very difficult to further analyze the area, the scope, as well as the surrounding structures of the abnormal point (e.g., points causing an open circuit or short circuit). Moreover, in the method, the layer can easily get damaged by the cutting, which can influence the result of the analysis.
Currently, the integration level of TFT array substrates is getting higher and higher, and TFT array substrates are provided with more and more layers which are superimposed one by one. Consequently, after all processes, a defective layer may be covered by other layers. Additionally, in color filter on array (COA) technology, a color resistance layer is also integrated onto the array substrate, which enables it even harder to detect the abnormal layer.
Therefore, in order to solve the above problem, a method for effectively positioning defects of a TFT array substrate is highly desirable.